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jonny [76]
3 years ago
8

Can anyone help me with this last question?

Physics
1 answer:
Digiron [165]3 years ago
6 0

Answer:

v = 39.6 m/s (first answer option)

Explanation:

Use conservation of mechanical energy.

The starting is completely potential energy and the final is all kinetic energy:

m*g*h=\frac{1}{2}*m*v^2\\g *  h=\frac{1}{2} v^2\\9.8*80=\frac{1}{2} v^2\\v^2=1568\\v\approx 39.6\,\,m/s

which agrees with the first answer shown.

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the ratio of the energy per second radiated by the filament of a lamp at 250k to that radiated at 2000k, assuming the filament i
Naily [24]

Answer:

(a) \frac{P_{250k}}{P_{2000k}}=2.4\ x\ 10^{-4}

(b) P =  0.816 Watt

Explanation:

(a)

The power radiated from a black body is given by Stefan Boltzman Law:

P = \sigma AT^4

where,

P = Energy Radiated per Second = ?

σ = stefan boltzman constant = 5.67 x 10⁻⁸ W/m².K⁴

T = Absolute Temperature

So the ratio of power at 250 K to the power at 2000 K is given as:

\frac{P_{250k}}{P_{2000k}}=\frac{\sigma A(250)^4}{\sigma A(2000)^4}\\\\\frac{P_{250k}}{P_{2000k}}=2.4\ x\ 10^{-4}

(b)

Now, for 90% radiator blackbody at 2000 K:

P = (0.9)(5.67\ x\ 10^{-8}\ W/m^2.K^4)(1\ x\ 10^{-6}\ m^2)(2000\ K)^4

<u>P =  0.816 Watt</u>

7 0
3 years ago
How do you find the total magnification of a microscope?
Alla [95]
In order to find total magnification of a microscope, you need to multiply the power of eyepiece and objective lens.

Hope this helps!
6 0
3 years ago
What is the density of a piece of quartz with a mass of 30g and a volume of 6cm^3
FromTheMoon [43]

Answer:

\boxed {\boxed {\sf d= 5 \ g/cm^3}}

Explanation:

Density can be found by dividing the mass by the volume.

d=\frac{m}{v}

The mass of the quartz is 30 grams and the volume is 6 cubic centimeters.

m=30 \ g \\v= 6 \ cm^3

Substitute the values into the formula.

d=\frac{30 \ g}{6 \ cm^3}

Divide.

d= 5 \ g/cm^3

The density of this piece of quartz is 5 grams per cubic centimeter.

7 0
3 years ago
A sample of gas has a volume of 215 cm3 at 23.5 °c and 84.6 kpa. what volume (cm3 will the gas occupy at stp
Dafna11 [192]
The answer is 165.3 cm³.

P1 * V1 / T1 = P2 * V2 / T2

The initial sample:
P1 = 84.6 kPa
V1 = 215 cm³
T1 = 23.5°C = 23.5 + 273 K = 296.5 K

At STP:
P2 = 101.3 kPa
V2 = ?
T2 = 273 K

Therefore:
84.6 * 215 / 296.5 = 101.3 * V2 / 273
61.34 = 101.3 * V2 / 273
V2 = 61.34 * 273 / 101.3
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LenKa [72]

Answer:Weight is the result of gravity . The gravitational field strength of Earth is 10 N/kg (ten newtons per kilogram). This means an object with a mass of 1 kg would be attracted towards the centre of Earth by a force of 10 N. We feel forces like this as weight.

Explanation:

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3 years ago
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